|"Trailing vortices" have a sink rate of several hundred feet/minute, depending on the aircraft. Wake turbulence abates only when enough time has pased or there's enough distance between the originting aircraft and the plane behind it.|
FAA's Guide To Avoiding Wake Turbulence
1 Takeoff. If you think that wake turbulence from the preceding aircraft may be a factor, tell the tower you'd like to wait—before taking the runway. Plan your takeoff, so you'll lift off before the rotation point of the other aircraft.
2 Climb. If possible, climb above the flightpath of the preceding aircraft. When that is not possible, deviate slightly upwind. Avoid headings that cause you to cross behind and below the preceding aircraft in order to avoid turbulence.
3 Crossing. If you must cross behind the preceding aircraft, try to cross above its flightpath or (terrain permitting) at least 1000 feet below.
4 Following. Stay either on or above the flightpath of the preceding aircraft.
5 Approach. Maintain a position on or above the preceding aircraft's flightpath.
6 Landing. Ensure that your touchdown point is beyond the preceding aircraft's touchdown point or land well before the departing aircraft's rotation point.
7 Crossing Approaches. When landing behind another aircraft on crossing approaches, it's wise to cross above the other aircraft's flightpath.
8 Crosswinds. Remember that crosswinds may affect the position of vortices. Adjust takeoff and landing points accordingly.
9 Helicopters. Helicopter wake vortices may be of significantly greater strength than fixed-wing aircraft of the same weight. Avoid flying beneath the flightpath of helicopters.